the first time i tried to build this, I used the smaller motors (1.5-3VDC Metal Gear Motors and 2 9volt batteries in series). I found the torque was low using the motor shield and I could only get 1 motor to work in one direction when I leaned the platform. I bought bigger motors and a RC battery to supply more power and hopefully create more torque.

Now, even with the bigger batteries and motors, I see 3/4 of the led lights above the motor terminals indicating the motor is working, but still only in 1 motor in 1 direction. I can't seem to figure out why the wheel that works doesn't turn in the other direction.

I tested both motors using one of the Digital Energy® 7.2V/2800mAh Ni-MH batteries, then reverse polarity, and found the motors work fine with high torque. I'm also getting a decent output on the pid program I'm using.

deuce_legend

ok. Thanks PaulS and zoomkat. I'll create the wiring diagram and upload today. Now, both motors work (I had a short in one wire), and I can get both wheels working in both directions.

PaulS - I started with the gyroscope and accelerometer and they were working fine before I added the motors. Now motors working ok, but I can't get the gyroscope and accelerometer to function as before.